It is generally known that a variety of connector interfaces (such as a USB (universal serial bus) interface, an AUX interface (audio input interface), a SD card (secure digital card) interface, a HDMI interface (high-definition multimedia interface), etc.) are often provided on an electronic device (such as a desktop computer, a laptop, a mobile phone, etc.). Since these interfaces need to connect with external connectors when these interfaces are used, these interfaces cannot be covered by a casing of the electronic device when these interfaces are used. For needs of the dust-proof, protection interface and beautiful appearance, protective covers can be used to cover these interfaces when these interfaces are not used. These protective covers are designed to be detachable so that they do not block the connection of the external connectors with these interfaces when these interfaces are required to use.
However, since the connector interfaces need to be used frequently, accordingly, these protective covers need to frequently cover and uncover, therefore, these protective covers are often lost due to that the operator forgets to cover the protective covers when the connector interfaces are not used.
In order to solve the above problem, a protective cover is disclosed in Chinese Patent Application No. 200710202572.8. As shown in FIG. 1, the protective cover 32 is made of plastic or soft rubber and is formed by an integral molding technique (e.g., injection molding). An inner surface 68 of a bottom plate 60 of a casing is provided with a fixing rod 64 which comprises a fixing end 642 and a free end 644 and substantially forms a T-shape, a mounting part 34 of the protective cover 32 passes through a through hole 620 of the bottom plate 60 of the casing and makes a sliding groove 342 sheathe onto the fixing end 642 of the fixing rod 64 so that the protective cover 32 can slide relative to the fixing rod 64. When the protective cover 32 is pulled out, the sliding groove 342 moves relative to the fixing rod 64, and when the fixing rod 64 contacts the lowermost end of the sliding groove 342, the fixing rod 64 prevents the protective cover 32 from being further pulled out.
However, as can be seen from the above disclosed content, the fixing rod 64 needs to be provided on the bottom plate 60 of the casing, the through hole 620 for passing and sheathing of the mounting part 34 also needs to be provided on the bottom plate 60 of the casing, these are all additional structures that are added on the casing. These additional structures will increase the complexity of the construction and the manufacturing difficulty of the casing. Moreover, one choice of the protective cover 32 is made of a hard plastic, or another alternative is made of soft rubber, both of which have their own disadvantages, for example, the operation is not easy to open the protective cover or close the protective cover, or feel is bad, or appearance is not beautiful and so on.